fair sure → fairly sure

'Fairly sure' is the standard form. Use the adverb fairly to modify the adjective sure. Dropping -ly leaves an adjective trying to modify another adjective, which is nonstandard in written English.

Quick answer

'Fairly sure' is correct. Use fairly (adverb) to modify sure (adjective). Avoid 'fair sure' in writing and in formal speech.

• 'Fairly' (adverb) + 'sure' (adjective) = fairly sure.
• 'Fair' is usually an adjective and does not modify adjectives.
• In casual speech some people drop -ly, but in writing use 'fairly sure' or another hedging adverb such as 'pretty sure' or 'quite sure' depending on tone.

Core explanation

Adverbs modify verbs, adjectives, or other adverbs. Since sure is an adjective, it needs an adverb like fairly. Writing 'fair sure' leaves an adjective (fair) attempting to modify another adjective (sure), which is nonstandard in grammar and looks like a typo.

Speakers may hear and reproduce the clipped form in casual conversation, but standard written English keeps the -ly. When you want a milder degree of confidence, choose 'fairly sure'; for stronger or weaker tones, use 'quite sure', 'pretty sure', or 'not very sure'.

Hyphenation and spacing

Keep 'fairly sure' as two separate words. Do not hyphenate in normal use. If you need a compound modifier before a noun, rephrase rather than hyphenating: instead of 'a fairly-sure conclusion', write 'a conclusion we're fairly sure about' or 'a fairly certain conclusion'.

Also, only replace 'fair' with 'fairly' when it directly modifies an adjective like sure. Blind global replacements can create errors in phrases where fair is an adjective on its own.

How it looks in real usage

Seeing correct and incorrect forms in context makes the pattern obvious. Below are natural sentences for work, school, and casual settings.

• Work - Wrong: I'm fair sure we can finish by Friday. -
  Right: I'm fairly sure we can finish by Friday.
• School - Wrong: She's fair sure she'll pass the exam. -
  Right: She's fairly sure she'll pass the exam.
• Casual - Wrong: I'm fair sure dinner's at six. -
  Right: I'm fairly sure dinner's at six.

Wrong vs right examples you can copy

Copy these pairs to practice spotting and fixing the error quickly.

• Wrong: I'm fair sure I'll get the promotion.
  Right: I'm fairly sure I'll get the promotion.
• Wrong: He's fair sure the answer is B.
  Right: He's fairly sure the answer is B.
• Wrong: We're fair sure the server will be back up soon.
  Right: We're fairly sure the server will be back up soon.
• Wrong: The paper is fair sure to be accepted after revisions.
  Right: The paper is fairly sure to be accepted after revisions.
• Wrong: Are you fair sure about the time?
  Right: Are you fairly sure about the time?
• Wrong: She sounded fair sure on the call.
  Right: She sounded fairly sure on the call.

How to fix your own sentence

Fixing the pattern is usually simple, but check tone and flow after the swap.

• Step 1: Identify whether the phrase modifies an adjective (e.g., sure).
• Step 2: Replace fair with fairly when it modifies an adjective.
• Step 3: Reread the sentence for tone; if the phrasing still sounds awkward, rewrite the sentence rather than forcing the phrase.

• Original: This plan is fair sure if everyone stays late.
  Rewrite: This plan is fairly sure if everyone stays late.
• Original: The assignment feels fair sure now.
  Rewrite: The assignment feels fairly sure now. (Or better: The assignment should be fine now.)
• Original: Is that fair sure this afternoon?
  Rewrite: Are you fairly sure about this afternoon?

Work, school, and casual rewrite examples

Three quick rewrites in each context to show alternatives that match tone and formality.

• Work
  • Wrong: I'm fair sure the client will approve.
    Right: I'm fairly sure the client will approve.
  • Wrong: The rollout is fair sure for next week.
    Right: The rollout is fairly sure for next week.
  • Rewrite alternative: I expect client approval next week.
• School
  • Wrong: I'm fair sure I answered question five correctly.
    Right: I'm fairly sure I answered question five correctly.
  • Wrong: The group project is fair sure to pass.
    Right: The group project is fairly sure to pass.
  • Rewrite alternative: The group project will probably pass.
• Casual
  • Wrong: I'm fair sure she'll like the gift.
    Right: I'm fairly sure she'll like the gift.
  • Wrong: Is it fair sure we're meeting at seven?
    Right: Are you fairly sure we're meeting at seven?
  • Rewrite alternative: I think we're meeting at seven.

A simple memory trick

Link form to function: picture fairly as the modifier doing the work. If a word is modifying an adjective, reach for an -ly adverb. Repeat a short checklist when you edit: adjective + adverb? Check for -ly.

• Hear the phrase aloud - 'fairly sure' has a natural cadence; 'fair sure' sounds clipped.
• Search your documents for "fair sure" and fix in bulk.
• Keep a short list of common swaps: fair → fairly, real → really, equal → equally.

Similar mistakes to watch for

Once the eye accepts one spacing or form error, nearby words can suffer. Scan for these related issues:

• split or joined words (e.g., all right vs alright)
• missing -ly on adverbs (e.g., real quick → really quick)
• hyphen confusion in compound modifiers (choose rephrasing over awkward hyphens)
• word-class confusion where an adjective is used where an adverb is needed

FAQ

Is 'fair sure' ever correct in speech or dialects?

Some dialects and casual speech drop the -ly and listeners will understand 'fair sure.' Still, it's nonstandard in writing and can sound off in formal speech. Use 'fairly sure' for clear, standard English.

Can I use 'pretty sure' instead?

'Pretty sure' is a common, idiomatic alternative in casual contexts. 'Fairly sure' is more neutral; 'quite sure' is stronger. Match the phrase to the tone you want.

Should I search-and-replace 'fair' with 'fairly' automatically?

No. Only change fair to fairly when it directly modifies an adjective (like sure). Use targeted searches for the phrase 'fair sure' or rely on a context-aware grammar checker to avoid false positives.

What about hyphenation like 'fairly-sure'?

Don't hyphenate. Keep 'fairly sure' as two words. For a compound modifier before a noun, rephrase: instead of 'a fairly-sure conclusion', write 'a conclusion we're fairly sure about' or 'a fairly certain conclusion'.

How can I stop making this mistake?

Use the three-step fix: spot, replace, polish. Read sentences aloud - the natural rhythm helps. Keep a short list of common swaps and search your drafts for 'fair sure' before sending important messages.

Quick fix now

Search your text for 'fair sure' and replace with 'fairly sure' where it modifies an adjective. Then read the sentence to check tone; if it still sounds awkward, rewrite the sentence for clarity.

If you want help polishing a sentence, paste it here and get 2-3 context-appropriate rewrites for work, school, or casual tone.